Abstract :
Background: Poly methyl methacrylate (PMMA) is widely used in dentistry as a denture base material. But the material has some inherent drawbacks in its mechanical properties like impact strength and flexural strength which can lead to fracture of the prosthesis. So the present study was conducted to evaluate and compare both impact and tensile strength in conventional acrylic resin and veined acrylic resin reinforced with one weight percentage titanium dioxide nanoparticles.
Objectives: 1. To determine and compare the effect of incorporation of titanium dioxide nanoparticles on tensile strength in megapascals between heat activated and veined acrylic denture base resins. 2. To determine and compare the effect of incorporation of titanium dioxide nanoparticles on impact strength in kilo joules per meter square between heat activated and veined acrylic denture base resins.
Materials and Methods: 80 specimens were prepared and grouped into Eight groups (A1, A2, B1, B2, C1, C2, D1, and D2) with10 specimens in each. Group A1, A2, B1 and B2 was used to study tensile strength and Group C1, C2, D1 and D2 was used to study impact strength. Group A1 and C1 were conventional heat cure acrylic, group A2 and C2 were the modified ones with one weight percentage (1wt%) titanium dioxide nanoparticles, groups B1 and D1 were veined acrylic, group B2 and D2 were the modified veined acrylic with 1wt% titanium dioxide nanoparticles. Tensile strength was tested using INSTRON universal testing machine and impact strength was tested using IZOD impact tester. Results were analyzed using independent t-test followed by Bonferroni’s correction to control the p value.
Results: Mean and standard deviation of tensile strength of group A1 was 53.2110.36 Mpa, group A2 was 56.873.96 Mpa, group B1 was 44.483.31Mpa and group B2 was 53.164.62 Mpa. The mean and standard deviation of impact strength of group C1 was 8.720.78 Kj/m2, group C2 was 10.100.40 Kj/m2, group D1 was 9.230.34 Kj/m2 and group D2 was 7.010.66 Kj/m2. Mean and standard deviation were subjected to the statistical analysis and p-value less than 0.05 is statistically significant. Tensile strength was significantly higher in titanium dioxide nanoparticles incorporated veined polymethyl methacrylate than
unmodified veined polymethyl methacrylate (p-value was 0.0001) while there was no significant change between the nanoparticles incorporated conventional heat cure acrylic and conventional heat cure acrylic resin. There was significant increase in impact strength of the modified conventional acrylic resin compared to the unmodified one but there was a significant decrease in impact strength of the modified veined resin compared to the unmodified veined ones.
Conclusion: The results showed an increase in tensile strength for veined acrylics and increase in the impact strength of conventional acrylic without much change in tensile strength after incorporation of titanium dioxide nanoparticle. Hence titanium dioxide nanoparticles can be incorporated into the conventional denture base material to improve the quality of the denture.
Keyword :
Nanoparticles incorporation, Titanium dioxide, Denture base impact strength, Denture base tensile strength.